Index: trunk/psModules/src/objects/pmSourceExtendedPars.c
===================================================================
--- trunk/psModules/src/objects/pmSourceExtendedPars.c	(revision 32347)
+++ trunk/psModules/src/objects/pmSourceExtendedPars.c	(revision 34403)
@@ -190,4 +190,7 @@
 bool pmSourceRadialProfileSortPair (psVector *index, psVector *extra) {
 
+    psAssert (index->n == extra->n, "mismatched vector lengths");
+    if (index->n < 2) return true;
+
     // sort the vector set by the radius
     PSSORT (index->n, COMPARE_INDEX, SWAP_INDEX, NONE);